The 2-point method offers a faster alternative to the commonly used multiple-point approach for force-velocity (F V) profiling, while preserving high accuracy and reliability in the measurement of maximum force (F0), velocity (V0), and power (Pmax). Therefore, it could be a promising method for the characterization of muscle function in older adults, using the loaded 5 Sit-to-Stand test (L5STS). The aim of the study was both to evaluate the validity and the reliability of a 2-point for F V profiling during L5STS and to identify the lowest “heaviest” load required to provide valid estimates of F0, V0 and Pmax. Fifty-six older adults (66.6 ± 5.7 years) performed the L5STS under four load conditions (body weight BW, BW + 12.5% BW +12.5% , BW + 25% BW +25% , and BW + 37.5% BW +37.5% ). Validity was assessed using linear mixed-effects models, Pearson's correlation, Lin's concordance correlation coefficient (CCC), standardized bias, and Bland-Altman analysis. Reliability was assessed using intraclass correlation coefficient, CCC, coefficient of variation, standard error of measurement, and minimal detectable change. The BW-BW +37.5% combination showed the best overall performance, with excellent concordance (CCC = 0.956–0.986), trivial standardized bias across all outcomes, narrow limits of agreement, and acceptable test-retest reliability. BW-BW +25% showed intermediate performance, being acceptable mainly for Pmax, whereas BW-BW +12.5% showed poor agreement and weaker reliability. These findings suggest that the 2-point method may be considered during the L5STS when sufficiently distant loads are selected, with BW-BW +37.5% showing the best agreement among the tested load combinations, in healthy older adults.
Bochicchio et al. (2026) studied this question.